Replace Audio track in MP4

[Ceyarrecks]

Excuse me please:
I am unsure if this is the correct sub-forum under Video Editing.
And please forgive my ignorance in general on video editing to begin with.
I have need to replace the audio track in an mp4 file, what software program would be best to accomplish this?

Thank you for your time in replying....

CAH

[poisondeathray]

mp4box (some GUI's you can use : yamb, mymp4boxgui)

[fvisagie]

You can also try Avidemux. Specify the replacement track as external audio source and set Video to copy to prevent recoding.